A conservative legal group is trying to force Gov. Arnold Schwarzenegger and Attorney General Jerry Brown to defend California's gay marriage ban in court.

The Pacific Justice Institute petitioned the 3rd District Court of Appeal in Sacramento on Monday for an emergency order that would require the two officials to appeal a ruling that overturned Proposition 8.

Chief U.S. District Judge Vaughn Walker struck down the voter-approved measure as unconstitutional last month.

Its sponsors have appealed. But doubts have been raised about whether they have authority to do so because as ordinary citizens they are not responsible for enforcing marriage laws.

The state has until Sept. 11 to challenge Walker's ruling in the 9th U.S. Circuit Court of Appeals. Both Brown and Schwarzenegger, who also refused to support Proposition 8 in Walker's court, have said they do not plan to.